The user might never look at all the tab pages in your Tab control. You can avoid the overhead of creating graphical representations of the controls on all the tab pages by checking Create on Demand on the Tab control’s General property page or setting the CreateOnDemand property to TRUE.
The controls on all the tab pages in a Tab control are always instantiated when the Tab control is created. However, when Create on Demand is checked, the Constructor event for controls on tab pages is not triggered and graphical representations of the controls are not created until the user views the tab page.
Constructor events on the selected tab page
Constructor events for controls on the selected tab
page are always triggered when the Tab control is created.
A window will open more quickly if the creation of graphical representations is delayed for tab pages with many controls. However, scripts cannot refer to a control on a tab page until the control’s Constructor event has run and a graphical representation of the control has been created. When Create on Demand is checked, scripts cannot reference controls on tab pages that the user has not viewed.
You can check whether a tab page has been created with the PageCreated function. Then, if it has not been created, you can trigger the constructor event for the tab page using the CreatePage function:
IF tab_1.tabpage_3.PageCreated() = FALSE THEN tab_1.tabpage_3.CreatePage() END IF
You can check whether a control on a tab page has been created by checking whether the control’s handle is nonzero. If so, the control has been created.
IF Handle(tab_1.tabpage_3.dw_list) > 0 THEN ...
If you change the CreateOnDemand property to FALSE in a script, graphical representations of any tab pages that have not been created are created immediately.
It does not do any good to change CreateOnDemand to TRUE during execution, because graphical representations of all the tab pages have already been created.
If CreateOnDemand is FALSE, you can set the label for a dynamically created tab page in its Constructor event, using the argument to OpenTabWithParm that is passed to the Message object. If CreateOnDemand is TRUE, you need to set the label when the tab page is instantiated, because the Constructor event is not triggered until the tab is selected. The following script in a user event that is posted from a window’s open event opens five tab pages and sets the label for each tab as it is instantiated:
int li_ctr string is_title THIS.setredraw(false) FOR li_ctr = 1 to 5 is_title = "Tab#" + string(li_ctr) tab_test.opentabwithparm(iuo_tabpage[li_ctr], & is_title, 0) iuo_tabpage[li_ctr].text = is_title //set tab label NEXT THIS.setredraw(true) RETURN 1
